Question

The frequency of a car horn is 400 Hz. If the horn is honked as the car moves with a speed $u_s$ = 34 m/s through still air towards a stationary receiver, the wavelength of the sound passing the receiver is [velocity of sound is 340 m/s]

• A. 0.765 m
• B. 0.850 m
• C. 0.935 m
• D. 0.425 m

Answer 1

The correct option is A 0.765 m

The wavelength in front of the car is
$\lambda =\frac{v-u_s}{f_s}=\frac{340\frac{m}{s}-34m/s}{400Hz}$
= 0.765 m